Washout effect in rabbit brain: in-beam PET measurements using 10C, 11C and 15O ion beams
Washout effect in rabbit brain: in-beam PET measurements using 10C, 11C and 15O ion beams
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DOI：
10.1088/2057-1976/aaade7
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发表时间：
2018-03
影响因子：
1.4
通讯作者：
C. Toramatsu;E. Yoshida;H. Wakizaka;A. Mohammadi;Y. Ikoma;H. Tashima;F. Nishikido;A. Kitagawa;K. Karasawa;Y. Hirano;T. Yamaya
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作者：
C. Toramatsu;E. Yoshida;H. Wakizaka;A. Mohammadi;Y. Ikoma;H. Tashima;F. Nishikido;A. Kitagawa;K. Karasawa;Y. Hirano;T. Yamaya
在粒子治疗中，束内正电子发射断层扫描（PET）有望实现原位无创确认治疗交付。然而，对于精确的范围和剂量验证或三维（3D）体积成像，需要校正活体中的生物洗脱效应。在这项研究中，我们测量了冲洗率在兔脑使用最近开发的技术，氧束辐射以及碳离子束辐射。为了测量冲洗成分，在千叶重离子医用加速器（HIMAC）中产生的三种放射性核素10 C、11 C和15 O在两种条件下（活的和死的）照射兔脑。通过我们的全身双环OpenPET采集射束内数据，可实现3D射束内成像。感兴趣区域（ROI）被设置为三维正电子分布，并获得照射野的时间活度曲线（TAC）。我们获得了洗脱率的基础上，这些条件的多组分模型分析。观察到11C离子和15O离子的洗脱速度之间的差异。11 C离子在兔脑中的中等和慢速生物衰变率分别为0.30 min−1和0.004 min−1。这些值与之前通过其他成像方式获得的兔子研究结果一致，例如正电子相机对或我们的单环小动物OpenPET原型。15O离子的中等和慢速生物衰变率分别为0.72 min−1和0.024 min−1，比11C离子快。此外，15O离子的介质生物衰减率接近于用15O标记水动态PET测量脑血流量（CBF）的洗脱率。这些结果将有助于建立一个准确的冲刷校正模型。
In particle therapy, in-beam positron emission tomography (PET) is expected to enable in situ noninvasive confirmation of the treatment delivery. For accurate range and dose verification or three-dimensional (3D) volume imaging, however, correction of the biological washout effect in a living body is necessary. In this study, we measured the washout rate in a rabbit brain using the recently developed technology for oxygen beam radiation as well as carbon ion beam radiation. To measure components of washout, three radionuclides, 10C, 11C and 15O, which were generated as secondary beams in the Heavy Ion Medical Accelerator in Chiba (HIMAC), were irradiated on the rabbit brain under two conditions, live and dead. In-beam data were acquired by our whole body dual-ring OpenPET, which enables 3D in-beam imaging. Regions of interests (ROIs) were set as a 3D positron distribution and the time activity curves (TACs) of the irradiated field were acquired. We obtained the washout rate for those conditions based on multiple component model analysis. A difference between washout speed in 11C ions and the 15O ions was observed. The observed medium and slow biological decay rates of 11C ions in rabbit brain were 0.30 min−1 and 0.004 min−1, respectively. Those values were consistent with the previous rabbit study results acquired by other imaging modalities, such as the pair of positron cameras or our single-ring small animal OpenPET prototype. The observed medium and slow biological decay rates of 15O ions were 0.72 min−1 and 0.024 min−1, respectively, which were faster than those of the 11C ion. Also, the medium biological decay rate of 15O ions was close to the washout rate in cerebral blood flow (CBF) measurements by dynamic PET with 15O-labeled water. These results should help to establish an accurate washout correction model.